/*
** $Id: lapi.c $
** Lua API
** See Copyright Notice in lua.h
*/

#define lapi_c
#define LUA_CORE

#include "lprefix.h"


#include <limits.h>
#include <stdarg.h>
#include <string.h>

#include "lua.h"

#include "lapi.h"
#include "ldebug.h"
#include "ldo.h"
#include "lfunc.h"
#include "lgc.h"
#include "lmem.h"
#include "lobject.h"
#include "lstate.h"
#include "lstring.h"
#include "ltable.h"
#include "ltm.h"
#include "lundump.h"
#include "lvm.h"



const char lua_ident[] =
    "$LuaVersion: " LUA_COPYRIGHT " $"
    "$LuaAuthors: " LUA_AUTHORS " $";



/*
** Test for a valid index.
** '!ttisnil(o)' implies 'o != &G(L)->nilvalue', so it is not needed.
** However, it covers the most common cases in a faster way.
*/
#define isvalid(L, o) (!ttisnil(o) || o != &G(L)->nilvalue)


/* test for pseudo index */
#define ispseudo(i)  ((i) <= LUA_REGISTRYINDEX)

/* test for upvalue */
#define isupvalue(i)  ((i) < LUA_REGISTRYINDEX)


static TValue *index2value (lua_State *L, int idx) {
    CallInfo *ci = L->ci;
    if (idx > 0) {
        StkId o = ci->func + idx;
        api_check(L, idx <= L->ci->top - (ci->func + 1), "unacceptable index");
        if (o >= L->top) return &G(L)->nilvalue;
        else return s2v(o);
    }
    else if (!ispseudo(idx)) {  /* negative index */
        api_check(L, idx != 0 && -idx <= L->top - (ci->func + 1), "invalid index");
        return s2v(L->top + idx);
    }
    else if (idx == LUA_REGISTRYINDEX)
        return &G(L)->l_registry;
    else {  /* upvalues */
        idx = LUA_REGISTRYINDEX - idx;
        api_check(L, idx <= MAXUPVAL + 1, "upvalue index too large");
        if (ttislcf(s2v(ci->func)))  /* light C function? */
            return &G(L)->nilvalue;  /* it has no upvalues */
        else {
            CClosure *func = clCvalue(s2v(ci->func));
            return (idx <= func->nupvalues) ? &func->upvalue[idx-1] : &G(L)->nilvalue;
        }
    }
}


static StkId index2stack (lua_State *L, int idx) {
    CallInfo *ci = L->ci;
    if (idx > 0) {
        StkId o = ci->func + idx;
        api_check(L, o < L->top, "unacceptable index");
        return o;
    }
    else {    /* non-positive index */
        api_check(L, idx != 0 && -idx <= L->top - (ci->func + 1), "invalid index");
        api_check(L, !ispseudo(idx), "invalid index");
        return L->top + idx;
    }
}


LUA_API int lua_checkstack (lua_State *L, int n) {
    int res;
    CallInfo *ci;
    lua_lock(L);
    ci = L->ci;
    api_check(L, n >= 0, "negative 'n'");
    if (L->stack_last - L->top > n)  /* stack large enough? */
        res = 1;  /* yes; check is OK */
    else {  /* no; need to grow stack */
        int inuse = cast_int(L->top - L->stack) + EXTRA_STACK;
        if (inuse > LUAI_MAXSTACK - n)  /* can grow without overflow? */
            res = 0;  /* no */
        else  /* try to grow stack */
            res = luaD_growstack(L, n, 0);
    }
    if (res && ci->top < L->top + n)
        ci->top = L->top + n;  /* adjust frame top */
    lua_unlock(L);
    return res;
}


LUA_API void lua_xmove (lua_State *from, lua_State *to, int n) {
    int i;
    if (from == to) return;
    lua_lock(to);
    api_checknelems(from, n);
    api_check(from, G(from) == G(to), "moving among independent states");
    api_check(from, to->ci->top - to->top >= n, "stack overflow");
    from->top -= n;
    for (i = 0; i < n; i++) {
        setobjs2s(to, to->top, from->top + i);
        to->top++;  /* stack already checked by previous 'api_check' */
    }
    lua_unlock(to);
}


LUA_API lua_CFunction lua_atpanic (lua_State *L, lua_CFunction panicf) {
    lua_CFunction old;
    lua_lock(L);
    old = G(L)->panic;
    G(L)->panic = panicf;
    lua_unlock(L);
    return old;
}


LUA_API lua_Number lua_version (lua_State *L) {
    UNUSED(L);
    return LUA_VERSION_NUM;
}



/*
** basic stack manipulation
*/


/*
** convert an acceptable stack index into an absolute index
*/
LUA_API int lua_absindex (lua_State *L, int idx) {
    return (idx > 0 || ispseudo(idx))
           ? idx
           : cast_int(L->top - L->ci->func) + idx;
}


LUA_API int lua_gettop (lua_State *L) {
    return cast_int(L->top - (L->ci->func + 1));
}


LUA_API void lua_settop (lua_State *L, int idx) {
    CallInfo *ci;
    StkId func;
    ptrdiff_t diff;  /* difference for new top */
    lua_lock(L);
    ci = L->ci;
    func = ci->func;
    if (idx >= 0) {
        api_check(L, idx <= ci->top - (func + 1), "new top too large");
        diff = ((func + 1) + idx) - L->top;
        for (; diff > 0; diff--)
            setnilvalue(s2v(L->top++));  /* clear new slots */
    }
    else {
        api_check(L, -(idx+1) <= (L->top - (func + 1)), "invalid new top");
        diff = idx + 1;  /* will "subtract" index (as it is negative) */
    }
    if (diff < 0 && hastocloseCfunc(ci->nresults))
        luaF_close(L, L->top + diff, LUA_OK);
    L->top += diff;  /* correct top only after closing any upvalue */
    lua_unlock(L);
}


/*
** Reverse the stack segment from 'from' to 'to'
** (auxiliary to 'lua_rotate')
** Note that we move(copy) only the value inside the stack.
** (We do not move additional fields that may exist.)
*/
static void reverse (lua_State *L, StkId from, StkId to) {
    for (; from < to; from++, to--) {
        TValue temp;
        setobj(L, &temp, s2v(from));
        setobjs2s(L, from, to);
        setobj2s(L, to, &temp);
    }
}


/*
** Let x = AB, where A is a prefix of length 'n'. Then,
** rotate x n == BA. But BA == (A^r . B^r)^r.
*/
LUA_API void lua_rotate (lua_State *L, int idx, int n) {
    StkId p, t, m;
    lua_lock(L);
    t = L->top - 1;  /* end of stack segment being rotated */
    p = index2stack(L, idx);  /* start of segment */
    api_check(L, (n >= 0 ? n : -n) <= (t - p + 1), "invalid 'n'");
    m = (n >= 0 ? t - n : p - n - 1);  /* end of prefix */
    reverse(L, p, m);  /* reverse the prefix with length 'n' */
    reverse(L, m + 1, t);  /* reverse the suffix */
    reverse(L, p, t);  /* reverse the entire segment */
    lua_unlock(L);
}


LUA_API void lua_copy (lua_State *L, int fromidx, int toidx) {
    TValue *fr, *to;
    lua_lock(L);
    fr = index2value(L, fromidx);
    to = index2value(L, toidx);
    api_check(L, isvalid(L, to), "invalid index");
    setobj(L, to, fr);
    if (isupvalue(toidx))  /* function upvalue? */
        luaC_barrier(L, clCvalue(s2v(L->ci->func)), fr);
    /* LUA_REGISTRYINDEX does not need gc barrier
       (collector revisits it before finishing collection) */
    lua_unlock(L);
}


LUA_API void lua_pushvalue (lua_State *L, int idx) {
    lua_lock(L);
    setobj2s(L, L->top, index2value(L, idx));
    api_incr_top(L);
    lua_unlock(L);
}



/*
** access functions (stack -> C)
*/


LUA_API int lua_type (lua_State *L, int idx) {
    const TValue *o = index2value(L, idx);
    return (isvalid(L, o) ? ttype(o) : LUA_TNONE);
}


LUA_API const char *lua_typename (lua_State *L, int t) {
    UNUSED(L);
    api_check(L, LUA_TNONE <= t && t < LUA_NUMTYPES, "invalid type");
    return ttypename(t);
}


LUA_API int lua_iscfunction (lua_State *L, int idx) {
    const TValue *o = index2value(L, idx);
    return (ttislcf(o) || (ttisCclosure(o)));
}


LUA_API int lua_isinteger (lua_State *L, int idx) {
    const TValue *o = index2value(L, idx);
    return ttisinteger(o);
}


LUA_API int lua_isnumber (lua_State *L, int idx) {
    lua_Number n;
    const TValue *o = index2value(L, idx);
    return tonumber(o, &n);
}


LUA_API int lua_isstring (lua_State *L, int idx) {
    const TValue *o = index2value(L, idx);
    return (ttisstring(o) || cvt2str(o));
}


LUA_API int lua_isuserdata (lua_State *L, int idx) {
    const TValue *o = index2value(L, idx);
    return (ttisfulluserdata(o) || ttislightuserdata(o));
}


LUA_API int lua_rawequal (lua_State *L, int index1, int index2) {
    const TValue *o1 = index2value(L, index1);
    const TValue *o2 = index2value(L, index2);
    return (isvalid(L, o1) && isvalid(L, o2)) ? luaV_rawequalobj(o1, o2) : 0;
}


LUA_API void lua_arith (lua_State *L, int op) {
    lua_lock(L);
    if (op != LUA_OPUNM && op != LUA_OPBNOT)
        api_checknelems(L, 2);  /* all other operations expect two operands */
    else {  /* for unary operations, add fake 2nd operand */
        api_checknelems(L, 1);
        setobjs2s(L, L->top, L->top - 1);
        api_incr_top(L);
    }
    /* first operand at top - 2, second at top - 1; result go to top - 2 */
    luaO_arith(L, op, s2v(L->top - 2), s2v(L->top - 1), L->top - 2);
    L->top--;  /* remove second operand */
    lua_unlock(L);
}


LUA_API int lua_compare (lua_State *L, int index1, int index2, int op) {
    const TValue *o1;
    const TValue *o2;
    int i = 0;
    lua_lock(L);  /* may call tag method */
    o1 = index2value(L, index1);
    o2 = index2value(L, index2);
    if (isvalid(L, o1) && isvalid(L, o2)) {
        switch (op) {
        case LUA_OPEQ:
            i = luaV_equalobj(L, o1, o2);
            break;
        case LUA_OPLT:
            i = luaV_lessthan(L, o1, o2);
            break;
        case LUA_OPLE:
            i = luaV_lessequal(L, o1, o2);
            break;
        default:
            api_check(L, 0, "invalid option");
        }
    }
    lua_unlock(L);
    return i;
}


LUA_API size_t lua_stringtonumber (lua_State *L, const char *s) {
    size_t sz = luaO_str2num(s, s2v(L->top));
    if (sz != 0)
        api_incr_top(L);
    return sz;
}


LUA_API lua_Number lua_tonumberx (lua_State *L, int idx, int *pisnum) {
    lua_Number n = 0;
    const TValue *o = index2value(L, idx);
    int isnum = tonumber(o, &n);
    if (pisnum)
        *pisnum = isnum;
    return n;
}


LUA_API lua_Integer lua_tointegerx (lua_State *L, int idx, int *pisnum) {
    lua_Integer res = 0;
    const TValue *o = index2value(L, idx);
    int isnum = tointeger(o, &res);
    if (pisnum)
        *pisnum = isnum;
    return res;
}


LUA_API int lua_toboolean (lua_State *L, int idx) {
    const TValue *o = index2value(L, idx);
    return !l_isfalse(o);
}


LUA_API const char *lua_tolstring (lua_State *L, int idx, size_t *len) {
    TValue *o;
    lua_lock(L);
    o = index2value(L, idx);
    if (!ttisstring(o)) {
        if (!cvt2str(o)) {  /* not convertible? */
            if (len != NULL) *len = 0;
            lua_unlock(L);
            return NULL;
        }
        luaO_tostring(L, o);
        luaC_checkGC(L);
        o = index2value(L, idx);  /* previous call may reallocate the stack */
    }
    if (len != NULL)
        *len = vslen(o);
    lua_unlock(L);
    return svalue(o);
}


LUA_API lua_Unsigned lua_rawlen (lua_State *L, int idx) {
    const TValue *o = index2value(L, idx);
    switch (ttypetag(o)) {
    case LUA_VSHRSTR:
        return tsvalue(o)->shrlen;
    case LUA_VLNGSTR:
        return tsvalue(o)->u.lnglen;
    case LUA_VUSERDATA:
        return uvalue(o)->len;
    case LUA_VTABLE:
        return luaH_getn(hvalue(o));
    default:
        return 0;
    }
}


LUA_API lua_CFunction lua_tocfunction (lua_State *L, int idx) {
    const TValue *o = index2value(L, idx);
    if (ttislcf(o)) return fvalue(o);
    else if (ttisCclosure(o))
        return clCvalue(o)->f;
    else return NULL;  /* not a C function */
}


static void *touserdata (const TValue *o) {
    switch (ttype(o)) {
    case LUA_TUSERDATA:
        return getudatamem(uvalue(o));
    case LUA_TLIGHTUSERDATA:
        return pvalue(o);
    default:
        return NULL;
    }
}


LUA_API void *lua_touserdata (lua_State *L, int idx) {
    const TValue *o = index2value(L, idx);
    return touserdata(o);
}


LUA_API lua_State *lua_tothread (lua_State *L, int idx) {
    const TValue *o = index2value(L, idx);
    return (!ttisthread(o)) ? NULL : thvalue(o);
}


/*
** Returns a pointer to the internal representation of an object.
** Note that ANSI C does not allow the conversion of a pointer to
** function to a 'void*', so the conversion here goes through
** a 'size_t'. (As the returned pointer is only informative, this
** conversion should not be a problem.)
*/
LUA_API const void *lua_topointer (lua_State *L, int idx) {
    const TValue *o = index2value(L, idx);
    switch (ttypetag(o)) {
    case LUA_VLCF:
        return cast_voidp(cast_sizet(fvalue(o)));
    case LUA_VUSERDATA:
    case LUA_VLIGHTUSERDATA:
        return touserdata(o);
    default: {
        if (iscollectable(o))
            return gcvalue(o);
        else
            return NULL;
    }
    }
}



/*
** push functions (C -> stack)
*/


LUA_API void lua_pushnil (lua_State *L) {
    lua_lock(L);
    setnilvalue(s2v(L->top));
    api_incr_top(L);
    lua_unlock(L);
}


LUA_API void lua_pushnumber (lua_State *L, lua_Number n) {
    lua_lock(L);
    setfltvalue(s2v(L->top), n);
    api_incr_top(L);
    lua_unlock(L);
}


LUA_API void lua_pushinteger (lua_State *L, lua_Integer n) {
    lua_lock(L);
    setivalue(s2v(L->top), n);
    api_incr_top(L);
    lua_unlock(L);
}


/*
** Pushes on the stack a string with given length. Avoid using 's' when
** 'len' == 0 (as 's' can be NULL in that case), due to later use of
** 'memcmp' and 'memcpy'.
*/
LUA_API const char *lua_pushlstring (lua_State *L, const char *s, size_t len) {
    TString *ts;
    lua_lock(L);
    ts = (len == 0) ? luaS_new(L, "") : luaS_newlstr(L, s, len);
    setsvalue2s(L, L->top, ts);
    api_incr_top(L);
    luaC_checkGC(L);
    lua_unlock(L);
    return getstr(ts);
}


LUA_API const char *lua_pushstring (lua_State *L, const char *s) {
    lua_lock(L);
    if (s == NULL)
        setnilvalue(s2v(L->top));
    else {
        TString *ts;
        ts = luaS_new(L, s);
        setsvalue2s(L, L->top, ts);
        s = getstr(ts);  /* internal copy's address */
    }
    api_incr_top(L);
    luaC_checkGC(L);
    lua_unlock(L);
    return s;
}


LUA_API const char *lua_pushvfstring (lua_State *L, const char *fmt,
                                      va_list argp) {
    const char *ret;
    lua_lock(L);
    ret = luaO_pushvfstring(L, fmt, argp);
    luaC_checkGC(L);
    lua_unlock(L);
    return ret;
}


LUA_API const char *lua_pushfstring (lua_State *L, const char *fmt, ...) {
    const char *ret;
    va_list argp;
    lua_lock(L);
    va_start(argp, fmt);
    ret = luaO_pushvfstring(L, fmt, argp);
    va_end(argp);
    luaC_checkGC(L);
    lua_unlock(L);
    return ret;
}


LUA_API void lua_pushcclosure (lua_State *L, lua_CFunction fn, int n) {
    lua_lock(L);
    if (n == 0) {
        setfvalue(s2v(L->top), fn);
        api_incr_top(L);
    }
    else {
        CClosure *cl;
        api_checknelems(L, n);
        api_check(L, n <= MAXUPVAL, "upvalue index too large");
        cl = luaF_newCclosure(L, n);
        cl->f = fn;
        L->top -= n;
        while (n--) {
            setobj2n(L, &cl->upvalue[n], s2v(L->top + n));
            /* does not need barrier because closure is white */
            lua_assert(iswhite(cl));
        }
        setclCvalue(L, s2v(L->top), cl);
        api_incr_top(L);
        luaC_checkGC(L);
    }
    lua_unlock(L);
}


LUA_API void lua_pushboolean (lua_State *L, int b) {
    lua_lock(L);
    if (b)
        setbtvalue(s2v(L->top));
    else
        setbfvalue(s2v(L->top));
    api_incr_top(L);
    lua_unlock(L);
}


LUA_API void lua_pushlightuserdata (lua_State *L, void *p) {
    lua_lock(L);
    setpvalue(s2v(L->top), p);
    api_incr_top(L);
    lua_unlock(L);
}


LUA_API int lua_pushthread (lua_State *L) {
    lua_lock(L);
    setthvalue(L, s2v(L->top), L);
    api_incr_top(L);
    lua_unlock(L);
    return (G(L)->mainthread == L);
}



/*
** get functions (Lua -> stack)
*/


static int auxgetstr (lua_State *L, const TValue *t, const char *k) {
    const TValue *slot;
    TString *str = luaS_new(L, k);
    if (luaV_fastget(L, t, str, slot, luaH_getstr)) {
        setobj2s(L, L->top, slot);
        api_incr_top(L);
    }
    else {
        setsvalue2s(L, L->top, str);
        api_incr_top(L);
        luaV_finishget(L, t, s2v(L->top - 1), L->top - 1, slot);
    }
    lua_unlock(L);
    return ttype(s2v(L->top - 1));
}


LUA_API int lua_getglobal (lua_State *L, const char *name) {
    Table *reg;
    lua_lock(L);
    reg = hvalue(&G(L)->l_registry);
    return auxgetstr(L, luaH_getint(reg, LUA_RIDX_GLOBALS), name);
}


LUA_API int lua_gettable (lua_State *L, int idx) {
    const TValue *slot;
    TValue *t;
    lua_lock(L);
    t = index2value(L, idx);
    if (luaV_fastget(L, t, s2v(L->top - 1), slot, luaH_get)) {
        setobj2s(L, L->top - 1, slot);
    }
    else
        luaV_finishget(L, t, s2v(L->top - 1), L->top - 1, slot);
    lua_unlock(L);
    return ttype(s2v(L->top - 1));
}


LUA_API int lua_getfield (lua_State *L, int idx, const char *k) {
    lua_lock(L);
    return auxgetstr(L, index2value(L, idx), k);
}


LUA_API int lua_geti (lua_State *L, int idx, lua_Integer n) {
    TValue *t;
    const TValue *slot;
    lua_lock(L);
    t = index2value(L, idx);
    if (luaV_fastgeti(L, t, n, slot)) {
        setobj2s(L, L->top, slot);
    }
    else {
        TValue aux;
        setivalue(&aux, n);
        luaV_finishget(L, t, &aux, L->top, slot);
    }
    api_incr_top(L);
    lua_unlock(L);
    return ttype(s2v(L->top - 1));
}


static int finishrawget (lua_State *L, const TValue *val) {
    if (isempty(val))  /* avoid copying empty items to the stack */
        setnilvalue(s2v(L->top));
    else
        setobj2s(L, L->top, val);
    api_incr_top(L);
    lua_unlock(L);
    return ttype(s2v(L->top - 1));
}


static Table *gettable (lua_State *L, int idx) {
    TValue *t = index2value(L, idx);
    api_check(L, ttistable(t), "table expected");
    return hvalue(t);
}


LUA_API int lua_rawget (lua_State *L, int idx) {
    Table *t;
    const TValue *val;
    lua_lock(L);
    api_checknelems(L, 1);
    t = gettable(L, idx);
    val = luaH_get(t, s2v(L->top - 1));
    L->top--;  /* remove key */
    return finishrawget(L, val);
}


LUA_API int lua_rawgeti (lua_State *L, int idx, lua_Integer n) {
    Table *t;
    lua_lock(L);
    t = gettable(L, idx);
    return finishrawget(L, luaH_getint(t, n));
}


LUA_API int lua_rawgetp (lua_State *L, int idx, const void *p) {
    Table *t;
    TValue k;
    lua_lock(L);
    t = gettable(L, idx);
    setpvalue(&k, cast_voidp(p));
    return finishrawget(L, luaH_get(t, &k));
}


LUA_API void lua_createtable (lua_State *L, int narray, int nrec) {
    Table *t;
    lua_lock(L);
    t = luaH_new(L);
    sethvalue2s(L, L->top, t);
    api_incr_top(L);
    if (narray > 0 || nrec > 0)
        luaH_resize(L, t, narray, nrec);
    luaC_checkGC(L);
    lua_unlock(L);
}


LUA_API int lua_getmetatable (lua_State *L, int objindex) {
    const TValue *obj;
    Table *mt;
    int res = 0;
    lua_lock(L);
    obj = index2value(L, objindex);
    switch (ttype(obj)) {
    case LUA_TTABLE:
        mt = hvalue(obj)->metatable;
        break;
    case LUA_TUSERDATA:
        mt = uvalue(obj)->metatable;
        break;
    default:
        mt = G(L)->mt[ttype(obj)];
        break;
    }
    if (mt != NULL) {
        sethvalue2s(L, L->top, mt);
        api_incr_top(L);
        res = 1;
    }
    lua_unlock(L);
    return res;
}


LUA_API int lua_getiuservalue (lua_State *L, int idx, int n) {
    TValue *o;
    int t;
    lua_lock(L);
    o = index2value(L, idx);
    api_check(L, ttisfulluserdata(o), "full userdata expected");
    if (n <= 0 || n > uvalue(o)->nuvalue) {
        setnilvalue(s2v(L->top));
        t = LUA_TNONE;
    }
    else {
        setobj2s(L, L->top, &uvalue(o)->uv[n - 1].uv);
        t = ttype(s2v(L->top));
    }
    api_incr_top(L);
    lua_unlock(L);
    return t;
}


/*
** set functions (stack -> Lua)
*/

/*
** t[k] = value at the top of the stack (where 'k' is a string)
*/
static void auxsetstr (lua_State *L, const TValue *t, const char *k) {
    const TValue *slot;
    TString *str = luaS_new(L, k);
    api_checknelems(L, 1);
    if (luaV_fastget(L, t, str, slot, luaH_getstr)) {
        luaV_finishfastset(L, t, slot, s2v(L->top - 1));
        L->top--;  /* pop value */
    }
    else {
        setsvalue2s(L, L->top, str);  /* push 'str' (to make it a TValue) */
        api_incr_top(L);
        luaV_finishset(L, t, s2v(L->top - 1), s2v(L->top - 2), slot);
        L->top -= 2;  /* pop value and key */
    }
    lua_unlock(L);  /* lock done by caller */
}


LUA_API void lua_setglobal (lua_State *L, const char *name) {
    Table *reg;
    lua_lock(L);  /* unlock done in 'auxsetstr' */
    reg = hvalue(&G(L)->l_registry);
    auxsetstr(L, luaH_getint(reg, LUA_RIDX_GLOBALS), name);
}


LUA_API void lua_settable (lua_State *L, int idx) {
    TValue *t;
    const TValue *slot;
    lua_lock(L);
    api_checknelems(L, 2);
    t = index2value(L, idx);
    if (luaV_fastget(L, t, s2v(L->top - 2), slot, luaH_get)) {
        luaV_finishfastset(L, t, slot, s2v(L->top - 1));
    }
    else
        luaV_finishset(L, t, s2v(L->top - 2), s2v(L->top - 1), slot);
    L->top -= 2;  /* pop index and value */
    lua_unlock(L);
}


LUA_API void lua_setfield (lua_State *L, int idx, const char *k) {
    lua_lock(L);  /* unlock done in 'auxsetstr' */
    auxsetstr(L, index2value(L, idx), k);
}


LUA_API void lua_seti (lua_State *L, int idx, lua_Integer n) {
    TValue *t;
    const TValue *slot;
    lua_lock(L);
    api_checknelems(L, 1);
    t = index2value(L, idx);
    if (luaV_fastgeti(L, t, n, slot)) {
        luaV_finishfastset(L, t, slot, s2v(L->top - 1));
    }
    else {
        TValue aux;
        setivalue(&aux, n);
        luaV_finishset(L, t, &aux, s2v(L->top - 1), slot);
    }
    L->top--;  /* pop value */
    lua_unlock(L);
}


static void aux_rawset (lua_State *L, int idx, TValue *key, int n) {
    Table *t;
    TValue *slot;
    lua_lock(L);
    api_checknelems(L, n);
    t = gettable(L, idx);
    slot = luaH_set(L, t, key);
    setobj2t(L, slot, s2v(L->top - 1));
    invalidateTMcache(t);
    luaC_barrierback(L, obj2gco(t), s2v(L->top - 1));
    L->top -= n;
    lua_unlock(L);
}


LUA_API void lua_rawset (lua_State *L, int idx) {
    aux_rawset(L, idx, s2v(L->top - 2), 2);
}


LUA_API void lua_rawsetp (lua_State *L, int idx, const void *p) {
    TValue k;
    setpvalue(&k, cast_voidp(p));
    aux_rawset(L, idx, &k, 1);
}


LUA_API void lua_rawseti (lua_State *L, int idx, lua_Integer n) {
    Table *t;
    lua_lock(L);
    api_checknelems(L, 1);
    t = gettable(L, idx);
    luaH_setint(L, t, n, s2v(L->top - 1));
    luaC_barrierback(L, obj2gco(t), s2v(L->top - 1));
    L->top--;
    lua_unlock(L);
}


LUA_API int lua_setmetatable (lua_State *L, int objindex) {
    TValue *obj;
    Table *mt;
    lua_lock(L);
    api_checknelems(L, 1);
    obj = index2value(L, objindex);
    if (ttisnil(s2v(L->top - 1)))
        mt = NULL;
    else {
        api_check(L, ttistable(s2v(L->top - 1)), "table expected");
        mt = hvalue(s2v(L->top - 1));
    }
    switch (ttype(obj)) {
    case LUA_TTABLE: {
        hvalue(obj)->metatable = mt;
        if (mt) {
            luaC_objbarrier(L, gcvalue(obj), mt);
            luaC_checkfinalizer(L, gcvalue(obj), mt);
        }
        break;
    }
    case LUA_TUSERDATA: {
        uvalue(obj)->metatable = mt;
        if (mt) {
            luaC_objbarrier(L, uvalue(obj), mt);
            luaC_checkfinalizer(L, gcvalue(obj), mt);
        }
        break;
    }
    default: {
        G(L)->mt[ttype(obj)] = mt;
        break;
    }
    }
    L->top--;
    lua_unlock(L);
    return 1;
}


LUA_API int lua_setiuservalue (lua_State *L, int idx, int n) {
    TValue *o;
    int res;
    lua_lock(L);
    api_checknelems(L, 1);
    o = index2value(L, idx);
    api_check(L, ttisfulluserdata(o), "full userdata expected");
    if (!(cast_uint(n) - 1u < cast_uint(uvalue(o)->nuvalue)))
        res = 0;  /* 'n' not in [1, uvalue(o)->nuvalue] */
    else {
        setobj(L, &uvalue(o)->uv[n - 1].uv, s2v(L->top - 1));
        luaC_barrierback(L, gcvalue(o), s2v(L->top - 1));
        res = 1;
    }
    L->top--;
    lua_unlock(L);
    return res;
}


/*
** 'load' and 'call' functions (run Lua code)
*/


#define checkresults(L,na,nr) \
     api_check(L, (nr) == LUA_MULTRET || (L->ci->top - L->top >= (nr) - (na)), \
 "results from function overflow current stack size")


LUA_API void lua_callk (lua_State *L, int nargs, int nresults,
                        lua_KContext ctx, lua_KFunction k) {
    StkId func;
    lua_lock(L);
    api_check(L, k == NULL || !isLua(L->ci),
              "cannot use continuations inside hooks");
    api_checknelems(L, nargs+1);
    api_check(L, L->status == LUA_OK, "cannot do calls on non-normal thread");
    checkresults(L, nargs, nresults);
    func = L->top - (nargs+1);
    if (k != NULL && yieldable(L)) {  /* need to prepare continuation? */
        L->ci->u.c.k = k;  /* save continuation */
        L->ci->u.c.ctx = ctx;  /* save context */
        luaD_call(L, func, nresults);  /* do the call */
    }
    else  /* no continuation or no yieldable */
        luaD_callnoyield(L, func, nresults);  /* just do the call */
    adjustresults(L, nresults);
    lua_unlock(L);
}



/*
** Execute a protected call.
*/
struct CallS {  /* data to 'f_call' */
    StkId func;
    int nresults;
};


static void f_call (lua_State *L, void *ud) {
    struct CallS *c = cast(struct CallS *, ud);
    luaD_callnoyield(L, c->func, c->nresults);
}



LUA_API int lua_pcallk (lua_State *L, int nargs, int nresults, int errfunc,
                        lua_KContext ctx, lua_KFunction k) {
    struct CallS c;
    int status;
    ptrdiff_t func;
    lua_lock(L);
    api_check(L, k == NULL || !isLua(L->ci),
              "cannot use continuations inside hooks");
    api_checknelems(L, nargs+1);
    api_check(L, L->status == LUA_OK, "cannot do calls on non-normal thread");
    checkresults(L, nargs, nresults);
    if (errfunc == 0)
        func = 0;
    else {
        StkId o = index2stack(L, errfunc);
        api_check(L, ttisfunction(s2v(o)), "error handler must be a function");
        func = savestack(L, o);
    }
    c.func = L->top - (nargs+1);  /* function to be called */
    if (k == NULL || !yieldable(L)) {  /* no continuation or no yieldable? */
        c.nresults = nresults;  /* do a 'conventional' protected call */
        status = luaD_pcall(L, f_call, &c, savestack(L, c.func), func);
    }
    else {  /* prepare continuation (call is already protected by 'resume') */
        CallInfo *ci = L->ci;
        ci->u.c.k = k;  /* save continuation */
        ci->u.c.ctx = ctx;  /* save context */
        /* save information for error recovery */
        ci->u2.funcidx = cast_int(savestack(L, c.func));
        ci->u.c.old_errfunc = L->errfunc;
        L->errfunc = func;
        setoah(ci->callstatus, L->allowhook);  /* save value of 'allowhook' */
        ci->callstatus |= CIST_YPCALL;  /* function can do error recovery */
        luaD_call(L, c.func, nresults);  /* do the call */
        ci->callstatus &= ~CIST_YPCALL;
        L->errfunc = ci->u.c.old_errfunc;
        status = LUA_OK;  /* if it is here, there were no errors */
    }
    adjustresults(L, nresults);
    lua_unlock(L);
    return status;
}


LUA_API int lua_load (lua_State *L, lua_Reader reader, void *data,
                      const char *chunkname, const char *mode) {
    ZIO z;
    int status;
    lua_lock(L);
    if (!chunkname) chunkname = "?";
    luaZ_init(L, &z, reader, data);
    status = luaD_protectedparser(L, &z, chunkname, mode);
    if (status == LUA_OK) {  /* no errors? */
        LClosure *f = clLvalue(s2v(L->top - 1));  /* get newly created function */
        if (f->nupvalues >= 1) {  /* does it have an upvalue? */
            /* get global table from registry */
            Table *reg = hvalue(&G(L)->l_registry);
            const TValue *gt = luaH_getint(reg, LUA_RIDX_GLOBALS);
            /* set global table as 1st upvalue of 'f' (may be LUA_ENV) */
            setobj(L, f->upvals[0]->v, gt);
            luaC_barrier(L, f->upvals[0], gt);
        }
    }
    lua_unlock(L);
    return status;
}


LUA_API int lua_dump (lua_State *L, lua_Writer writer, void *data, int strip) {
    int status;
    TValue *o;
    lua_lock(L);
    api_checknelems(L, 1);
    o = s2v(L->top - 1);
    if (isLfunction(o))
        status = luaU_dump(L, getproto(o), writer, data, strip);
    else
        status = 1;
    lua_unlock(L);
    return status;
}


LUA_API int lua_status (lua_State *L) {
    return L->status;
}


/*
** Garbage-collection function
*/
LUA_API int lua_gc (lua_State *L, int what, ...) {
    va_list argp;
    int res = 0;
    global_State *g;
    lua_lock(L);
    g = G(L);
    va_start(argp, what);
    switch (what) {
    case LUA_GCSTOP: {
        g->gcrunning = 0;
        break;
    }
    case LUA_GCRESTART: {
        luaE_setdebt(g, 0);
        g->gcrunning = 1;
        break;
    }
    case LUA_GCCOLLECT: {
        luaC_fullgc(L, 0);
        break;
    }
    case LUA_GCCOUNT: {
        /* GC values are expressed in Kbytes: #bytes/2^10 */
        res = cast_int(gettotalbytes(g) >> 10);
        break;
    }
    case LUA_GCCOUNTB: {
        res = cast_int(gettotalbytes(g) & 0x3ff);
        break;
    }
    case LUA_GCSTEP: {
        int data = va_arg(argp, int);
        l_mem debt = 1;  /* =1 to signal that it did an actual step */
        lu_byte oldrunning = g->gcrunning;
        g->gcrunning = 1;  /* allow GC to run */
        if (data == 0) {
            luaE_setdebt(g, 0);  /* do a basic step */
            luaC_step(L);
        }
        else {  /* add 'data' to total debt */
            debt = cast(l_mem, data) * 1024 + g->GCdebt;
            luaE_setdebt(g, debt);
            luaC_checkGC(L);
        }
        g->gcrunning = oldrunning;  /* restore previous state */
        if (debt > 0 && g->gcstate == GCSpause)  /* end of cycle? */
            res = 1;  /* signal it */
        break;
    }
    case LUA_GCSETPAUSE: {
        int data = va_arg(argp, int);
        res = getgcparam(g->gcpause);
        setgcparam(g->gcpause, data);
        break;
    }
    case LUA_GCSETSTEPMUL: {
        int data = va_arg(argp, int);
        res = getgcparam(g->gcstepmul);
        setgcparam(g->gcstepmul, data);
        break;
    }
    case LUA_GCISRUNNING: {
        res = g->gcrunning;
        break;
    }
    case LUA_GCGEN: {
        int minormul = va_arg(argp, int);
        int majormul = va_arg(argp, int);
        res = isdecGCmodegen(g) ? LUA_GCGEN : LUA_GCINC;
        if (minormul != 0)
            g->genminormul = minormul;
        if (majormul != 0)
            setgcparam(g->genmajormul, majormul);
        luaC_changemode(L, KGC_GEN);
        break;
    }
    case LUA_GCINC: {
        int pause = va_arg(argp, int);
        int stepmul = va_arg(argp, int);
        int stepsize = va_arg(argp, int);
        res = isdecGCmodegen(g) ? LUA_GCGEN : LUA_GCINC;
        if (pause != 0)
            setgcparam(g->gcpause, pause);
        if (stepmul != 0)
            setgcparam(g->gcstepmul, stepmul);
        if (stepsize != 0)
            g->gcstepsize = stepsize;
        luaC_changemode(L, KGC_INC);
        break;
    }
    default:
        res = -1;  /* invalid option */
    }
    va_end(argp);
    lua_unlock(L);
    return res;
}



/*
** miscellaneous functions
*/


LUA_API int lua_error (lua_State *L) {
    TValue *errobj;
    lua_lock(L);
    errobj = s2v(L->top - 1);
    api_checknelems(L, 1);
    /* error object is the memory error message? */
    if (ttisshrstring(errobj) && eqshrstr(tsvalue(errobj), G(L)->memerrmsg))
        luaM_error(L);  /* raise a memory error */
    else
        luaG_errormsg(L);  /* raise a regular error */
    /* code unreachable; will unlock when control actually leaves the kernel */
    return 0;  /* to avoid warnings */
}


LUA_API int lua_next (lua_State *L, int idx) {
    Table *t;
    int more;
    lua_lock(L);
    api_checknelems(L, 1);
    t = gettable(L, idx);
    more = luaH_next(L, t, L->top - 1);
    if (more) {
        api_incr_top(L);
    }
    else  /* no more elements */
        L->top -= 1;  /* remove key */
    lua_unlock(L);
    return more;
}


LUA_API void lua_toclose (lua_State *L, int idx) {
    int nresults;
    StkId o;
    lua_lock(L);
    o = index2stack(L, idx);
    nresults = L->ci->nresults;
    api_check(L, L->openupval == NULL || uplevel(L->openupval) <= o,
              "marked index below or equal new one");
    luaF_newtbcupval(L, o);  /* create new to-be-closed upvalue */
    if (!hastocloseCfunc(nresults))  /* function not marked yet? */
        L->ci->nresults = codeNresults(nresults);  /* mark it */
    lua_assert(hastocloseCfunc(L->ci->nresults));
    lua_unlock(L);
}


LUA_API void lua_concat (lua_State *L, int n) {
    lua_lock(L);
    api_checknelems(L, n);
    if (n > 0)
        luaV_concat(L, n);
    else {  /* nothing to concatenate */
        setsvalue2s(L, L->top, luaS_newlstr(L, "", 0));  /* push empty string */
        api_incr_top(L);
    }
    luaC_checkGC(L);
    lua_unlock(L);
}


LUA_API void lua_len (lua_State *L, int idx) {
    TValue *t;
    lua_lock(L);
    t = index2value(L, idx);
    luaV_objlen(L, L->top, t);
    api_incr_top(L);
    lua_unlock(L);
}


LUA_API lua_Alloc lua_getallocf (lua_State *L, void **ud) {
    lua_Alloc f;
    lua_lock(L);
    if (ud) *ud = G(L)->ud;
    f = G(L)->frealloc;
    lua_unlock(L);
    return f;
}


LUA_API void lua_setallocf (lua_State *L, lua_Alloc f, void *ud) {
    lua_lock(L);
    G(L)->ud = ud;
    G(L)->frealloc = f;
    lua_unlock(L);
}


void lua_setwarnf (lua_State *L, lua_WarnFunction f, void *ud) {
    lua_lock(L);
    G(L)->ud_warn = ud;
    G(L)->warnf = f;
    lua_unlock(L);
}


void lua_warning (lua_State *L, const char *msg, int tocont) {
    lua_lock(L);
    luaE_warning(L, msg, tocont);
    lua_unlock(L);
}



LUA_API void *lua_newuserdatauv (lua_State *L, size_t size, int nuvalue) {
    Udata *u;
    lua_lock(L);
    api_check(L, 0 <= nuvalue && nuvalue < USHRT_MAX, "invalid value");
    u = luaS_newudata(L, size, nuvalue);
    setuvalue(L, s2v(L->top), u);
    api_incr_top(L);
    luaC_checkGC(L);
    lua_unlock(L);
    return getudatamem(u);
}



static const char *aux_upvalue (TValue *fi, int n, TValue **val,
                                GCObject **owner) {
    switch (ttypetag(fi)) {
    case LUA_VCCL: {  /* C closure */
        CClosure *f = clCvalue(fi);
        if (!(cast_uint(n) - 1u < cast_uint(f->nupvalues)))
            return NULL;  /* 'n' not in [1, f->nupvalues] */
        *val = &f->upvalue[n-1];
        if (owner) *owner = obj2gco(f);
        return "";
    }
    case LUA_VLCL: {  /* Lua closure */
        LClosure *f = clLvalue(fi);
        TString *name;
        Proto *p = f->p;
        if (!(cast_uint(n) - 1u  < cast_uint(p->sizeupvalues)))
            return NULL;  /* 'n' not in [1, p->sizeupvalues] */
        *val = f->upvals[n-1]->v;
        if (owner) *owner = obj2gco(f->upvals[n - 1]);
        name = p->upvalues[n-1].name;
        return (name == NULL) ? "(no name)" : getstr(name);
    }
    default:
        return NULL;  /* not a closure */
    }
}


LUA_API const char *lua_getupvalue (lua_State *L, int funcindex, int n) {
    const char *name;
    TValue *val = NULL;  /* to avoid warnings */
    lua_lock(L);
    name = aux_upvalue(index2value(L, funcindex), n, &val, NULL);
    if (name) {
        setobj2s(L, L->top, val);
        api_incr_top(L);
    }
    lua_unlock(L);
    return name;
}


LUA_API const char *lua_setupvalue (lua_State *L, int funcindex, int n) {
    const char *name;
    TValue *val = NULL;  /* to avoid warnings */
    GCObject *owner = NULL;  /* to avoid warnings */
    TValue *fi;
    lua_lock(L);
    fi = index2value(L, funcindex);
    api_checknelems(L, 1);
    name = aux_upvalue(fi, n, &val, &owner);
    if (name) {
        L->top--;
        setobj(L, val, s2v(L->top));
        luaC_barrier(L, owner, val);
    }
    lua_unlock(L);
    return name;
}


static UpVal **getupvalref (lua_State *L, int fidx, int n, LClosure **pf) {
    static const UpVal *const nullup = NULL;
    LClosure *f;
    TValue *fi = index2value(L, fidx);
    api_check(L, ttisLclosure(fi), "Lua function expected");
    f = clLvalue(fi);
    if (pf) *pf = f;
    if (1 <= n && n <= f->p->sizeupvalues)
        return &f->upvals[n - 1];  /* get its upvalue pointer */
    else
        return (UpVal**)&nullup;
}


LUA_API void *lua_upvalueid (lua_State *L, int fidx, int n) {
    TValue *fi = index2value(L, fidx);
    switch (ttypetag(fi)) {
    case LUA_VLCL: {  /* lua closure */
        return *getupvalref(L, fidx, n, NULL);
    }
    case LUA_VCCL: {  /* C closure */
        CClosure *f = clCvalue(fi);
        if (1 <= n && n <= f->nupvalues)
            return &f->upvalue[n - 1];
        /* else */
        }  /* FALLTHROUGH */
    case LUA_VLCF:
        return NULL;  /* light C functions have no upvalues */
    default: {
        api_check(L, 0, "function expected");
        return NULL;
    }
    }
}


LUA_API void lua_upvaluejoin (lua_State *L, int fidx1, int n1,
                              int fidx2, int n2) {
    LClosure *f1;
    UpVal **up1 = getupvalref(L, fidx1, n1, &f1);
    UpVal **up2 = getupvalref(L, fidx2, n2, NULL);
    api_check(L, *up1 != NULL && *up2 != NULL, "invalid upvalue index");
    *up1 = *up2;
    luaC_objbarrier(L, f1, *up1);
}


